This invention relates to techniques for measuring with a Color Measurement System and evaluating the color of skin, teeth, hair and material substances with a Color Index. The invention also relates to techniques for using such a Color Measurement System with the Color Index in medical applications such as the detection of chromogenic disease including bilirubin infant jaundice, cosmetics applications and in the evaluation of the color of hair or teeth and other applications.
It is well known that color measuring instruments, such as spectrocolorimeters and spectrophotometers, can be used to measure the color of surfaces for a variety of useful applications. For example, Macfarlane et al. U.S. Pat. No. 5,313,267 describes a method and instrument for selecting personal compatible colors using a color measuring device. Also, PCT Publication No. WO 96/41140 describes methods and apparatus for determining the condition of a test subject based on color by using a color measuring instrument to detect change in a color factor indicative of a condition such as a disease, spoilage, ageing, etc. In particular, those methods and apparatus can be used to detect a medical condition known as hyperbilirubinemia by measuring skin color.
However, in order to accurately categorize skin versus each other (or teeth, hair or material substances, respectively), it is important that the Color Index used by the Color Measurement System for evaluating the color of skin, teeth, hair and material substances be independent of the illuminating condition and need not be calculated with respect to some standard illuminating condition. The alternative, allowing the Color Index to be dependent upon the conditions of illumination, would allow one sample (such as skin) to be categorized in one illuminating condition and another sample (such as skin) to be categorized in another illuminating condition, preventing any useful correlation of the colors of the two measurements.
It would be beneficial to develop a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a Color Index for skin, teeth, hair and material substances that makes a unique formulation of the opponent process of human vision. It is known that the contribution of redness and of greenness are in opponency to each other. Similarly, it is also known that the contribution of yellowness and of blueness are in opponency to each other. In other words, no color can exhibit qualities of redness and greenness at the same time, nor can a color exhibit qualities of yellowness and blueness at the same time. It would thus be beneficial to develop a Color Index for skin, teeth, hair and material substances that makes a unique formulation of the opponent process of human vision.
It would also be beneficial to develop a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a unique Color Index which is measured and calculated from the contribution of the reflectance spectrum of any skin (or teeth, hair, or material substance) to the appearance of four opponent colors, i.e., red-green and yellow-blue.
Furthermore, it would also be beneficial if the opponent process of human vision be formulated linearly with respect to the opponent contributions to color appearance rather than as an exponential function of the contributions as is conventionally held necessary for opponent-type systems.
In view of the foregoing, it is an object of this invention to provide a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a Color Index.
It is another object of this invention to provide a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a Color Index, wherein the Color Index is calculated from the contribution of the reflectance spectrum of any skin (or teeth, hair, or material substance) to the appearance of four opponent colors, i.e., red-green and yellow-blue.
It is yet another object of this invention to provide a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a Color Index that makes a unique formulation of the opponent process of human vision.
It is another object of this invention to provide a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a Color Index in which the opponent process is formulated linearly with respect to the opponent contributions to color appearance rather than as an exponential function of the contributions.
It is another object of this invention to provide a Color Measurement System for evaluating the color of skin, teeth, hair and material substances with a Color Index that is independent of the illuminating condition.